The prevalence of cancer is rapidly rising in the UK, with recent figures showing that 1 in 3 people will suffer from cancer. This article will explain how cancer works, how it is caused and what precautions can be taken to minimise risk of cancer.
What is cancer?
Cancer cells are human cells that have had their DNA damaged which can result in over-expression or suppression of one or more genes. These mutations can effect the rest of the genetic code and cause further mutations to occur. A cancer cell is characterised as an immortal cell which reproduces at an uncontrollable rate. Bellow are some common examples of genetic mutations which cause cancerous cells to develop. Often it can only take 1 of the following mutation for cells to become cancerous, but as the cancer develops it is more and more likely to have more of these mutations.
Cancer cells are often referred to as ‘immortal’ cells because they cannot die in the same way normal human cells die. All cells have natural mechanisms which induce apoptosis (cell death) if the cell is too damaged or too old. Apoptosis causes the cell to destroy itself, but if the mechanisms for this are damaged themselves then the cells cannot be destroyed. An example of this is a mutation in the APC gene, which encodes for a protein that is required for inducing apoptosis in cells. In 85% of colorectal cancer cases there has been a mutation in this gene, which has prevented the cell from destroying itself.
Uncontrollable Cell Proliferation & Reproduction
Cancer cells are able to replicate which causes the cancer to grow and spread. This is usually a result of mutations and/ or over expression of oncogenes which are responsible for cell division and proliferation. Oncogenes are part of the programmed cell apoptosis mechanism, but mutated oncogenes force the cell to proliferate and replicate. A common mutation is in the gene K-ras which is a proto-oncogene (a mutation causes it to become an oncogene). K-ras is important in regulation of cell growth and division, and is commonly found in cancer cells to be continuously signalling cell growth and division.
Mutated or Suppressed Defense Genes
Our genetic code is extremely sophisticated in that it has genes which code for proteins which repair damaged DNA. An example of this is a gene called p53, which stimulates repair of damaged DNA, and can also induce apoptosis in cells which are too damaged. If this gene is damaged itself then it is unable to fulfill its role, meaning DNA damage will not get repaired and apoptosis cannot be induced via its actions. The p53 gene is also referred to as the ‘tumor suppressor’ gene as it is so important in preventing cell abnormalities from persisting.
Causes for Genetic Mutations
Genetic mutations can occur naturally in DNA during replication for cell division. During this process bases in the DNA code can be deleted, swapped or added which can effect one or more genes. DNA can also be damaged by free radicals in the cell which react with DNA strands, damaging and altering one or more genes. These types of mutation are surprisingly regular, however, the body has built in precautions such as DNA repair proteins (coded for by p53 gene), and ‘programmed’ cell death (apoptosis) which occurs when the cell is damaged, which act as natural anti-cancer mechanisms. The immune system is also capable of identifying and destroying cancerous cells. These built in defense mechanisms are usually enough to protect the body from cancer cells developing. This can be seen throughout nature, with many species having no incidence of cancer, as their bodies are naturally protecting themselves.
It is when the number of genetic mutations rises above the level the body can handle, or when the natural defences are compromised that cancer cells can start to develop and advance.
Causes of Increased Mutations
One of the main contributors to genetic mutations is damage to DNA from free radicals. If the number of free radicals in the body is above the threshold that the immune system can manage, then the chances of a cancerous cell developing is drastically increased.
Levels of free radicals are increased from environmental factors, the most common being pollutants in the air, and toxins in our food. Pollutants in the air are found in higher concentrations in large cities, putting people living in these areas at a greater risk. The most common inhaled pollutant is smoke, which is thought to be the direct cause of 87% of lung cancer patients. Foods high in free radicals are usually highly processed or cooked at high temperatures such as frying. This damages and alters compounds found in the food into highly reactive species. Some foods such as large oily fish also contain pollutants such as PCB’s and methyl mercury.
Cell respiration also produces a very reactive radical called superoxide. The superoxide radical is a bi-product of the production of energy, and so large amount of exercise will produce more of this radical which can damage cells. This radical is so harmful that our cells produce an enzyme call superoxide dismutase which breaks down superoxide. As long as the production of this enzyme is not impaired, then the body will be able to minimise the potential damage of superoxide on the cell. This emphasises the importance of a healthy diet for people who regularly exercise.
Causes of Compromised Cancer Defenses
The bodies natural defenses can be compromised by the increased number of radicals (as explained above) as this will tax the defences more than usual. However, they can be further compromised by other aspects of your lifestyle.
In order to create immune cells, the body requires enough of the nutrient ‘building blocks’ to make them (such as the mineral selenium), if the diet does not provide enough of these nutrients then these immune cells cannot be made in the required quantities to protect the body.
Dietary antioxidants also can play an important role in preventing radical damage. There are a vast range of antioxidants which we can find in the diet, from the well know fat soluble vitamin E to the lesser known waters soluble anthocyanins. A wide variety of these antioxidants are needed to provide the body with a diverse and complete radical defense If the diet is lacking in antioxidant nutrients then the chances of a radical damaging DNA is increased.
Stages of Cancer
Once a cancer cell has been created and doesn’t get destroyed the development of the cancers can be seen in 5 progressive stages:
Stage 0 is defined as carcinoma in situ. This is characterized by a small number of cancerous cells which have developed in a localized area and have not penetrated the basement membrane. Some cancers such as many forms of bladder cancer progress no further than this which makes them relatively easy to remove.
The number of cancer cells is still low and in an early stage of development. Cancer cells are localized to one area in the body still but may have penetrated the basement membrane. More genetic mutations are present in these cancer cells.
Cancer cells are still localized to one part of the body, but the cells are considered to be advanced. A significantly larger number of mutations are present in the genetic code, and the number of cancerous cells has greatly increased.
This stage is referred to as late local advanced stage, and is characterized by further spreading of cancer cells in a localized area (i.e one organ). This stage is only significantly different from stage 2 in certain types of cancer.
This is the final stage of cancer development and is commonly known as metastasis. At this point in development the cancer can spread throughout the body and effect other organs, the number of genetic mutations are extensive and further growth is rapid.
Steps to Prevent Cancer
There are precautions which can drastically reduce the risk of getting cancer. Living in more rural areas away from pollutants of cities will reduce the intake of pollutants, and so reduce the risk of oxidative stress. A diet high in micro-nutrients will allow the body to actively defend itself against developing cancer cells and preventing DNA damage. Especially nutrients such as selenium, Vitamin C, vitamin E, which are well documented immune supporting nutrients.
Polyphenols have been shown to induce apoptosis in cancer cells which have already developed. It is not fully understood how these nutrients work, but they have also shown to posses a number of health benefits. Polyphenols are found in fruits and vegetables and are often high in brightly coloured ones.
Cancer is a modern illness, and is a result of a modern lifestyle. Exposing the body to an unnatural diet and environment results in an increased amount of stress on the body, which can result in DNA damage and cancer cell development. Cancer cells are immortal cells which have uncontrollable growth, and once developed can rapidly spread throughout the affected organ, and then the rest of the body.